SOURCES OF FAT IN ANIMAL BODY 541 



hydrate — > fat transformation, 116-118 Tepperman et al. 119 proved that it can 

 likewise take place in extrahepatic tissues. In the case of rats, trained to 

 ingest large amounts of a high-carbohydrate diet within a short period, 

 the R.Q. rose to 1.2% shortly following the feeding; when evisceration was 

 carried out immediately after the food was ingested, the resultant R.Q. was 

 shown to be 0.95. However, when insulin was also injected, an R.Q. of 1.16 

 was observed. These results are interpreted to indicate that the pe- 

 ripheral tissues are able to convert carbohydrate to fat when a sufficient 

 supply of carbohydrate is available. 119 



The results of the Yale group support the earlier data of Tuerkischer and 

 Wertheimer 120 indicating that the synthesis of fat may occur in the adipose 

 tissue itself. When fasted rats were placed on a diet rich in carbohydrate, 

 glycogen in concentrations of 1% was found to accumulate in the adipose 

 tissues after realimentation for periods up to four days. It is suggested by 

 these workers not only that the adipose tissues can synthesize glycogen, 

 but also that they can effect the synthesis of fat. These observations were 

 further supported by the results of Henle and Szpingier, 121 who demon- 

 strated that, in the isolated adipose tissue of the rat, the R.Q. rose above 

 unity simultaneously with the disappearance of glucose. In an extension 

 of this work, Mirski 122 was able to demonstrate that the adipose tissue of 

 rats could phosphorylate glycogen to form glucose-1-phosphate, as well as 

 to synthesize the polysaccharide from this ester. Moreover, when adipose 

 tissue obtained from such rats was suspended in a glucose-serum medium, 

 an R.Q. of 1.27 was found; similar adipose tissue obtained from fasted rats 

 was also observed to exhibit an R.Q. of 1.15. These data indicate that the 

 adipose deposit should probably not be considered as an indifferent and 

 passive tissue but as one which can synthesize glycogen and oxidize car- 

 bohydrate, and which likewise can convert carbohydrate to fat. 



c. The Mechanism of the Transformation of Carbohydrate to Fat. Up 

 to the present time, we have no exact information as to the intermediary 

 changes required to effect the transformation of carbohydrate to fat. 



116 T. P. Hilditch, The Chemical Constitution of Natural Fats, 2nd ed., Wiley, New 

 York, 1947. 



117 W. R. Bloor, Physiol. Revs., 19, 557-577 (1939). 



118 R. Schoenheimer, The Dynamic State of Body Constituents, Harvard Univ. Press, 

 Cambridge, 1942. 



119 J. Tepperman, J. R. Brobeck, and C. N. H. Long, Yale J. Biol. Med., 15, 855-874 

 (1943). 



120 E. Tuerkischer and E. Wertheimer, /. Physiol, 100, 385-409 (1941-1942). 



121 Henle and W. G. Szpingier, Arch, exptl. Path. Pharmakol. (Naunyn-Schmiedberg's) 

 180, 672-689(1936). 



122 E. Mirski, Biochem. J., 36, 232-241 (1942). 



